Recoilless flamethrower



Jan. 9, 1962 J. c. SMITH 3,016,086

RECOILLESS FLAMETHROWER Filed Sept. 24, 1959 2 Sheets-Sheet 1 l\INVENTOR M John a. smim ATTORNEY Jan. 9, 1962 J. c. SMl TH RECOILLESSFLAMETHROWER 2 Sheets-Sheet 2 Filed Sept. 24, 1959 R mm m W5 0 n M JATTORNEY Patented Jan. 9, 1962 3,016,086 RECGILEESS FLAMETHROWER John'C. Smith, .l23'McCol'miek St.,,B'el Air, Md; Filed'Sept 24; 1959-, Ser.No. 842,169: 1- Claim. (@l. 158-28) (Granted under Title 35, US. Code(1952), see. 266) The invention. described herein may be manufacturedand used" by or for the Government of the United States. of America forgovernmental purposes without the payment to me ofany, royalty thereon.

This invention relates to a recoilless, multi-shot, chemi cally ignited,portable flamethrower.

The primary object" of this invention is to provide a. portablemulti-shot flamethrower having a. range com-- parable to the usualvehicle-mounted or. mechanized flamethrowers.

Another object is to provide a versatile recoilless projector suitablefor projecting either a. stream of. liquid or a container a considerabledistance.-

In the drawing,

FIG. 1 is a side view of one modification. with parts shown in sectionand with the fuel supply. shown diagrammatically.

FIG. 2 is a perspective view of themuzzle: assembly of the flamethrowerof FIG; 1.

FIG. 3 is a section of'the fuel. discharge. valve forminga part of themuzzle assembly ofFIG. 2.

FIG; 4 is a section of the igniter disohargecap forming a part ofthemuzzle assembly of FIG. 2.

FIG. 5 is a view partially insection and partially in elevation of thefuel discharge nozzle.

FIG. 6 is an elevation of. the muzzle end. of the flamethrower with thefuel discharge nozzle removed to conv'ert the flamethrower to a mortar.or projector for hurling containers of incendiary fuel or the like.

FIG. 7 is an. elevation of a secondmodification of the flamethrower,partially in section.

Flamethrowers are important. military weapons, particularlly for use inassaults on fortified positions. They are also very efiective weaponsforuse. by infantry against tanks. The flamethrowers which are standardequipment at present comprise. a pressurized tank. of fuel connected toa projector or gun. The pressurized tank is supplied. with gas from a.pressure bottle under still higher pressure. These flamethrowers arequite heavy for carrying by an individual soldier in combat, yet theyare not readily handled by a team. The effective range of the portableflamethrowers is comparatively low, on the order of 60 to 70 yds. Theso-called mechanized flamethrowers attain a range up to 200 yds. but,because of their weight and heavy recoil, must be mounted on tanks orother vehicles. These flamethrowers require rather compli-- catedpressure. reduction valves between the pressure bottle and the fuel tankand are relatively expensive. Oneshot fiamethrowers which utilize apositive displacement piston have been developed which have a somewhatgreater range than the conventional portable flamethrower. But, as theirname indicates, they will fire only a single burst of burning fuel.

The flamethrower constituting the invention herein described has a rangecomparable to that of the mechanized flamethrower, yet is readilyportable and is therefore suitable for use by infantry. Since the fuelsupply isreadily disconnected from the flamethrower it'can be carried byanother; man, or by'severalmen, thus making it practical to providearelatively large source'of fuel; Because of the recoilless constructionthe fuel can be projected over a long range while the flamethrower isheld by an individual. The ignition system which is employedfissimple'and'also positive in its operation and only simple valvesarerequired, The entireapparatus is simple and'easily constructed.

Referring to the drawing the flamethrower includes a barrel 1, a muzzle;assembly indicated geenrally at. 3, mounted at the first or muzzle;endof the barrel, a convergent=diverg ent nozzle 5, at; the.v second endof the bar rel, a propellant gas-supply means indicated generally at 7and a fuel supply indicated generally. at 91 Thebarrel 1 is acylindrical tube which may be, for

' example, four inches inside diameter and six feet. long.

The propellant gas supply means 7 and-hand-grip'll' are rigidly mountedon the barrel, 11' Within the barrel is a freeplu nger 1-3 which ispreferably a ball. formed of oil resistant synthetic rubber.

The muzzle asesmbly 3, best shown in FIGv 2, will now be described. Itincludes a discharge nozzle 15 which is shown separately in FIG. 5. Thedischarge. nozzle 15 is removably attached to barrel 1 by means of screwthreads 171 The smaller end of nozzle 15 is threaded at 19 to receivethe valve assembly 21 which is separately shown in FIG; 3.

Valve assembly 21 includes a cylinder 23', carrying. a fixed plate 25.Plate 25, in turn carries a threaded discharge nipple 27 which isscrewed into threads 19 and nozzle 15. Within the cylinder 23 is piston29 which is urged downwardly by spring31. Piston 29 carries a valveplate 33 having an aperture 35. It also carries anigniter tube support37. Pinch valve 39 is also mounted on piston 29- and in. its closedposition, shown in FIG. 3., engages top-plate 41' of cylinder 23. Athreaded connection 43 completes the valve assembly.

The discharge nozzle 15 also'carries an igniter support 45 whichreceives a. pressurized container 47. Thecontainer 47 contains achemical ignition material, e.g.,

' chromyl nitrate,.and is removable from support 45. Flexible ignitertube 49 serves to deliver. the chemical ignitionmaterial into contactwith the fuel upon discharge. The tube 49'is' connected to a hollowneedle 51 which isv mounted in a cap 53 provided with. sealing means 55.The cap 53 is provided with pins 57 which form part of a bayonet: typeconnection with support 45. Container 47 is. likewise held in place by abayonet type connection. The tube 49 is engaged by pinch valve 39 and isaccordingly closed when the valve 21 is in the closed position shown inFIGURE 3. The end of tube 49 passes through an opening in tube support37 and is thereby held in the desired position.

A liquid supply line connector 59 is joined to nozzle 15 by threads 61'.The liquid supply line connector 59 contains a check valve 63 soconstructedas to open inwardly only.

The fuel or other liquid supply means 9 includes a tank 65 which ispressurized by, for example, a carbon dioxide bottle 67. The tank 65 isjoined to connector 5? by a flexible hose 69. The hose 69 is preferablyjoined to connector 59 and tank 65 by conventional quick-disconnectcouplings.

The convergent-divergent nozzle 5 has one end 71 of the same diameter asbarrel 1 and joined thereto by a threaded connection. The other end 73is open to the atmosphere. Between the two ends of the nozzle is aconstriction 75. A propellent gas inlet connection 77 joins the nozzle 5at a point between the constriction 75 and its junction with barrel 1.

The propellent gas supply 7 may be of either one of two types. One typeis shown in FIGURE 1 and the other in FIGURE 7. The type shown in FIGURE1 will be described first.

This supply means includes a housing 79 which is provided with ahand-grip 81 and encloses a cylinder 83 having a plurality of chambers85. A firing mechanism including a striker 87 and a trigger 89 is alsoincluded. The cylinder 83, the striker 87 and the trigger 89 areconstructed in the same manner as the corresponding parts of an ordinarydouble action revolver, except that the cylinder and its chambers are ofconsiderably larger size. Any conventional trigger and striker mechanismmay be employed and the details form no part of my invention.

Cartridges containing a propellant charge and a primer are inserted inchambers 85 and will be fired in the usual manner by mechanism 87, 89,thereby supplying the propellent gas to inlet connection 77.

In FIGURE 7 I have shown a different type of propellent gas supply whichmakes use of a decomposable liquid propellant. The propellant iscontained in a replacable tank 91 which is pressurized by means of acarbon dioxide bottle 93. The trigger 95 operates a valve, not shown,which admits propellant to the decomposing unit 97. This unit contains acatalyst 99. which decomposes propellant forming large quantities ofpropellent gases.

Near the muzzle end of barrel 1 is a limit switch 105 which is actuatedby plunger 13 and which operates, through connector 107, to cut olf theflow of propellant. This serves to prevent forward recoil due to thecontinued generation of propellent gases after the projected fuel isexhausted. i

In each of the modificationsthere is a 1' connection 101 between thepropellent gas generator means 7 and the propellent gas inlet 77. This Tis joined to a tube 103 which is connected at 43 to the cylinder 23.Thus when propellent gas is admitted to convergent-divergent nozzle 5 itis also admitted to cylinder 23, actuating piston 29.

The propellants used in this device have the same characteristics as tospeed of reaction as typical rocket fuels.

The liquid propellant utilized in the embodiment of FIG. 7 is one whichspontaneously decomposes under the desired conditions without detonationto give large volumes of gases and/or vapors. One such liquid isconcentrated (70% to 100%) hydrogen peroxide. The catalyst 99 ispreferably silver, in such form as to give a large surface area, or asilver-activated metal, such as copper, iron, or cobalt. Such catalystsare disclosed in the following patents: 2,887,476 to T. B. Halford etal., 2,811,490 to B. J. Sherwood, 2,809,940 to J. P. Crum, 2,750,346 toB. J. Sherwood, and 2,849,408 to Bente. Another class of suitablecatalysts make use of e permaganates, particularly calcium permanganate,as disclosed in US. Patents 2,584,127 to W. M. Harcum et al. and2,605,609 to R. B. Bush. A suitable catalyst of this type may be verysimply prepared by soaking fragments of pumice or other porous stone ina saturated solution of calcium permanganate and allowing it to dry.

Still another suitable liquid propellant is nitromethane, used incombination with a catalyst formed of manganese, copper, cobalt andsilver oxides as disclosed in Patent 2,433,932 to A. Stozick or lithiumaluminum tetrahydride as disclosed in US. Patent 2,648,190 to Maisner.

The solid propellants used in the embodiment of FIG. 1 are of therelatively slow-burning type. They should burn continuously at pressuresin the range of about 300 to 1000 pounds per square inch. Those used inrocket assisted take off units (often popularly termed jet assistedtakeoff or JATO units) are suitable. For example, I have successfullyused a mixture of about 80% potassium perchlorate and 20 percentasphalt, by weight. Other propellants of this type are described inSolid Propellant Rockets by A. J. Zaehringer published 1958 by theAmerican Rocket Co., Box 1112, Wyandotte, Michigan, pages 58-78 and194-228.

The propellants and catalysts as such are not my invention.

Operation It will be assumed that the device is charged with fuel and incondition to be fired. The plunger 13 will be at the extreme left-handend of the barrel 1 in FIGS; 1 and 7, and resting against the innerconical surface of nozzle 5. The entire barrel is filled with anincendiary fluid, ordinarily gelled gasoline. The operator pulls thetrigger 89 (FIG. 1) or (FIG. 7), admitting a large burst of propellentgases into nozzle 5. At the same time gas is admitted through tube 103into cylinder 23. This raises piston 29, bringing valve opening 35 intoregistry with discharge nipple 27. At the same time pinch valve 39 isopened. The propellent gases admitted to nozzle 5 expand in bothdirections, propelling plunger 13 toward the muzzle end of barrel 1 andat the same time rushing out through constriction 75 and open end 73 ofnozzle 5. Since aperture 35 is in registry with nipple 27 the nozzle 15is open and the incendiary fluid is ejected at high velocity. Since tube49 is open, the chemical igniter in pressurized container 47 flows outand contacts the stream of incendiary fuel, thus igniting it. Theaccelleration of gas through open end 73 of nozzle 5 creates a reactionwhich modifies the recoil which would otherwise result from theaecelleration of the fuel through nozzle 15. When the plunger 13 hasreached its extreme right-hand position any remaining propellent gasexhausts through nozzle 5 until substantially atmospheric pressure isattained. When the pressure in barrel 1 falls below that in fuelcontainer 65, fuel flows through tube 69, connector 59 and check valve63 into barrel 1, pushing plunger 13 back to its original position. Atthe same time spring 31 pushes piston 29 downward, closing dischargenipple 27 and pinch valve 39. The apparatus is then in condition to befired again.

Since nozzle 15 is readily separable from barrel 1 the latter may beleft open at its nozzle as shown in FIG. 6. The apparatus may then serveas a recoilless mortar or projector for hurling containers aconsiderable distance.

Furthermore the device may be used with the muzzle assembly 3 attached,but omitting the ignition mecha-- nism, to project non-bruning liquids.For example, it may be used to project a stream of water for use in firefighting.

Because of the combination of the cylindrical barrel, the externalgenerator of a sudden burst of propellent gas, and the anti-recoilnozzle the device is extremely versatile.

While I have described certain embodiments of my invention in detail, itwill be obvious that various changes are possible. I therefore wish myinvention to be limited solely by the scope of the appended claims.

I claim:

A multi-shot, recoilless flamethrower comprising a cylindrical barrel, adischarge nozzle at a first end of said barrel, a convergent-divergentnozzle at the second end of said barrel, a piston actuated valvearranged to open and close said discharge nozzle and comprising a springurging said valve toward its closed position; said convergent-divergentnozzle comprising a first end having the same diameter as said barreland joined thereto, a second end open to the atmosphere, and aconstruction between said ends; trigger operated generating meansexterior of said barrel and said nozzles for generating propellent gasesunder pressure, means for introducing said propellent gases into saidconvergent-divergent nozzle between said constriction and said barrel,means for simultaneously applying the propellent gas to said piston toopen said valve against the force of said spring: a freely movableaolaose ERNEST W. SWIDEYRJ,

5 6 plunger within said barrel and substantially closing the ReferencesCited in the file of this patent same adapted to be moved bysaidpropellent gas toward UNITED STATES PATENTS said first end of saidbarrel to end fuel from said d1scharge nozzle when said valve is open,means responsive 113041710 Seldler May 27, 1919 to the opening of saidvalve for igniting said fuel as it is 5 1380135 8 cfmke June 1921ejected from said nozzle; a fuel supply line connector 1,914,250 GluenJune 1933 mounted on an opening into said discharge nozzle, and 2389747Kamp et June 9, 1959 comprising a check valve opening inwardly only, afuel 219221341 Treat 1960 supply tank adapted to contain fuel underpressure, and 2,952,309 Fay P 1960 a detachable fuel supply line joiningsaid tank and said 10 connector.

UNITED STATE S PATENT OFFICE Patent No6 3,016,086 January 9, 1962 John CSmith bove numbered pat- It is hereb certified that error appears in thea ent requiring cozrection and that the said Letters Batent should readas corrected belowl Column 4, line 48, for "non hruning" readnon-burning line 67, for "construction read constrlctlon Signed andsealed this 8th day of May 196 (SEAL) 18ttest:

DANUDInIAJH) Attesting Officer-n Commissioner of Patents

